White-flowered Rhododendron (Rhododendron albiflorum)

We went for a hike on August 23, 2021 to Umbrella Falls, Mount Hood, Mount Hood National Forest starting at the Elk Meadows Trailhead and then up to the falls on the Umbrella Falls Trail. Two known small patches of R. albiflorum were noted along Elk Meadows Trail at an elevation of about 4550 ft in rills (small gullies) above (west of) the trail. A third patch, at an elevation of about 4575 ft, was noted a hundred or so yards west of the Elk Meadows Trail north of the Umbrella Falls Trail. And finally a fourth patch as noted at about elevation 5125 near the Hood River Express ski lift.

At the first location north of the Elk Meadows Trailhead parking flowering had taken place as evidenced by many fruiting bodies. A good photo was obtained showing the location of this year's flowers on the stem above last year's seed pods. R. albiflorum is unique among Rhododendrons in that flowering takes place on the previous year's stem, and not from a terminal bud as in other Rhododendrons. see:https://www.inaturalist.org/observations/92326390
No flowering was evidenced at the 2nd location. see: https://www.inaturalist.org/observations/92503915
At the third location on the lower Umbrella Falls we noted foliage eaten by caterpillars, aphids, and later with microscopic investigation spider mites and an interesting large aphid, as well as two ubiquitous (for R. albiflorum) fungal infections. see: https://www.inaturalist.org/observations/92325595 which includes links to additional related observations.
The fourth and highest elevation observation on 8/23/21 (see: https://www.inaturalist.org/observations/92321447 and: https://www.inaturalist.org/observations/92316642 ) had plants growing in full sun in the ski runs and plants growing in shade. Those growing in conditions with more light have leaves that tend to have wavy/crinkly appearances, while those growing in shadier conditions have leaves that are flat.

Posted on 25 de agosto de 2021, 08:56 PM by geographerdave